function plot_barycentric
v1 = [1,1.5];
v2 = [0,0];
v3 = [2,0];
T = [1,2,3];
V = [v1;v2;v3];
figure('Position',[100,100,350,300]);
plot_t(V,T);hold on;
text(v1(1)-0.03,v1(2)+0.05,'v_1','Color','red','FontSize',15);
text(v2(1)-0.05,v2(2)-0.05,'v_2','Color','red','FontSize',15);
text(v3(1),v3(2)-0.05,'v_3','Color','red','FontSize',15);
vx = 0.9; vy = 0.45;
plot(vx,vy,'r.');
text(vx+0.05,vy,'v(x,y)','FontSize',15);
axis tight; axis off;hold off;